1. Field of the Invention
This invention relates to flying shears for cropping the front and tail ends of hot rolled steel rods and other like products being delivered from a continuous high speed rolling mill.
2. Description of the Prior Art
Rods, bars, and other like long products produced by a continuous hot rolling process inevitably have off gauge front and tail ends that must be xe2x80x9ccroppedxe2x80x9d, i.e., severed and discarded. This can be accomplished by manual trimming after the products have left the rolling line. However, manual trimming requires the constant attention of mill personnel, and is both inefficient and expensive.
Preferably, therefore, cropping is effected by so-called xe2x80x9cflying shearsxe2x80x9d designed to operate automatically on line at mill delivery speeds. Although flying shears have operated successfully in the past, improvements in their design have failed to keep pace with ever increasing mill delivery speeds, which in modern day high speed rod mills are now reaching 100-120 m/sec.
The objective of the present invention is the provision of an improved flying shear which is fully capable of operating reliably at all mill delivery speeds, including the highest delivery speeds of modern day rod mills.
A shear in accordance with one aspect of the present invention has leader and follower blades contrarotating continuously at equal angular velocities. The blades coact in a radially overlapping relationship at a cutting zone spaced vertically from the plane of product movement, with the leader blade preceding the follower blade, and with the radius of rotation of the leader blade being longer than that of the follower blade. A switch upstream of the cutting zone operates in one mode to direct a product along a path bypassing the cutting zone, and in a second mode to direct the product through the cutting zone for cutting by the contrarotating blades into leading and trailing segments. The blades are configured to deflect the tail end of the leading segment away from the plane of product movement while directing the front end of the trailing segment back to the plane of product movement.
In accordance with another aspect of the present invention, the shear is preferably provided with two sets of the aforesaid blades arranged in a side-by-side arrangement, one set being operable to crop a product front end, and the other set being operable to crop the product tail end.
In accordance with still another aspect of the present invention, the cropped ends and intermediate acceptable product lengths are received in the separate guide passageways of a stationary trough located downstream of the cutting zone. Chopping shears operate to subdivide the cropped ends into shorter scrap pieces.
These and other features and objectives of the present invention will now be described in great detail with reference to the accompanying drawings, wherein: